The invention relates to a method for correcting positioning errors in rock drilling, where a boom, attached from one end to a carrier and turnable in relation to it about joints, and a rock drill, mounted turnable to the other end of the boom, are arranged in the drilling position for drilling a hole in a way that the boom is controlled using control devices of the drilling rig in relation to various movements until the boom is in its set position, wherein the deviation of the boom's actual position from the calculated theoretical position is measured, and the boom's position is corrected on the basis of the measured deviation.
Further, the invention is related to a rock drilling equipment, with a carrier, a boom attached turnable about joints in relation to the carrier, a rock drill attached turnable to the other end of the boom, joint sensors indicating the positions of the various boom joints, and control devices for controlling the boom to the drilling position for drilling a hole.
Higher and higher precision is required of the operation of a rock drilling rig so that excavating could be made as economic as possible. Today, automatic drilling boom positioning and controlling devices are more often used with the purpose of enabling the holes to be drilled as precisely as possible at their intended positions. For practical controlling purposes, various types of joint sensors are attached to booms, and the aim is to take into account the geometrical dimensions of the booms and their kinematics as well as possible when calculating the drill position and direction. The problem with automatic control solutions realized in this manner is, however, that different types of deflections, clearances and other things causing error result in that the actual position of the drill bit may considerably differ from the position where it should be according to the plan.
U.S. Pat. No. 4,698,570 presents a solution where the aim is to correct errors of known equipment by dividing the operating range of the drilling boom, i.e., the reach of the boom in one carrier position, into squares and with a specific correction value assigned for each square in all directions of the coordinate system. This is achieved in practice by setting the equipment to control the boom and the feed beam so that the drill bit is, in theory, at the center of the square in question, after which the errors in the different directions are measured and fed into the memory of the control equipment. In normal drilling use, the rig corrects the boom and feed beam positions in accordance with the square at which the intended hole position is located on the basis of the stored, fixed correction values of the square in question. The problem with this solution is that a tight grid must be used for the area to be drilled in order to get sufficient correction data for the various boom positions. Further, as the drill bit can be positioned at one specific location using a number of different boom positions, a correction system based on the mere location of the drill bit is unable to compensate for the different errors based on different boom positions and, thus, the intended precision is not reached.